1. Field of the Invention
The present invention relates to a data demodulator and a data demodulating method capable of demodulating n-tuple speed data (where n is a positive integer) such as sound, image, etc. in the digital form, which are input from an information supply source such as a CD-ROM drive, into M.multidot.n-tuple speed data (where M is a positive integer and M.gtoreq.2) in real time and then outputting M.multidot.n-tuple speed modulated data.
2. Description of the Prior Art
In recent years, various information reproducing devices for reproducing digital data such as sound, image, etc. stored in an information storing medium such as CD (Compact Disc), CD-ROM, etc. have been rapidly spread.
In particular, for example, in a CD-ROM drive which can play the digital data stored in the CD-ROM, a higher data transfer speed is pushed forward in answer to the request to play smoothly multimedia soft such as music, moving picture, etc. This higher data transfer speed can be achieved as an integral multiple of a standard speed of 1.50 Kbyte/sec which is a data transfer speed of a music CD player.
In the above situation that such higher data transfer speed is pushed forward day after day, there have been on the market various CD-ROM drives which can play the digital data in mutually different tuple speed modes such as double speed, treble speed, quadruple speed, sextuple speed, octuple speed, nonuple speed, etc. according to plural standards respectively.
However, in the above situation that the CD-ROM drives which are operated in mutually different tuple speed modes according to plural standards have been brought to the market, there has been a to-be-overcome drawback, for example, that there is a possibility of bringing about such a situation that the digital data which are reproduced at a tuple speed mode, e.g., double speed, treble speed, quadruple speed, octuple speed, etc. peculiar to a certain CD-ROM drive and then transmitted therefrom at a predetermined transfer speed cannot be received by an image reproducing unit on the receiver side.
The above situation has occurred in the event that the data transfer speed on the receiver side does not coincide with the data transfer speed on the transmitter side. In order not to bring about such situation, there has been such a disadvantage for the user of the CD-ROM drive in expanding the user's system that not only the user has to prepare another receiver side device which is able to receive the digital data at the transfer speed corresponding to the tuple speed mode of his or her own CD-ROM drive, but also the user has to newly introduce another transmitter side device with a different tuple speed mode into the user's system after an image reproducing system has been constructed by combining the CD-ROM drive as the transmitter side device with the image reproducing unit as the receiver side device, for instance.